I am trying to prevent showing a symbol when a user clicks on an edit button.

I do this like so:

var form = document.forms[1];
var data = document.getElementsByTagName("td");
var fixOrPerc = data["Sales-" + intID].innerHTML;

form.SalesFixed.value = fixOrPerc.substring(1, fixOrPerc.length - 1);
This does work correctly when i have a value like so:

But the problem is that i allow negative numbers like so

When negative numbers are entered and the edit button is clicked on then it removed the minus sign but keeps the symbol..

How can i fix this?

Hope someone can help..

Many thanks,